5. Relevant considerations & irrelevant considerations
Every decision made by public authorities requires taking a basket of factors into considerations. However, decision-makers must distinguish between relevant and irrelevant factors. Further, they must take into account all relevant factors, and disregard irrelevant ones. Typical valid considerations would include:
(1) criteria and purposes laid down by statute;
(2) relevant policies;
(3) circumstances and merits of each individual case.
Examples of invalid considerations would include: (1) political factors (unless specifically stated); (2) any personal feelings / emotions of the decision-maker.
Do note however that an irrelevant consideration must be material or substantial before it taints the legality of a decision.
For an illustration of this see Epoch Group Ltd v Director of Immigration [2011] 3 HKLRD H2, where the Director of Immigration (in refusing employment visas to backstage personnel of a certain arts group) failed to take into consideration the importance of a trusted, and well-rehearsed lighting and sound crew used to work with a particular group of performers, while irrelevantly considering the large amount of unrelated lighting and sound crews that are available in Hong Kong.